Norwegian world No 10 Casper Ruud dumped Andy Murray out of the San Diego Open with a 7-5, 6-4 win to reach the quarter-finals.

Ruud, who is the second seed at the event, will next play ninth-seeded Italian Lorenzo Sonego, who beat American young gun Sebastian Korda 6-4, 6-3.

Murray is down at No 109 in the ATP rankings having struggled with hip issues in recent years.

Ruud, though, heaped praise on his former world No 1 opponent.

“On the opposite side of the net from me was a legend of the game [from] the past decade or so. Even what he’s done now the past [few] years, fighting his way back from a very serious injury, it’s been an inspiration for me,” Ruud said in his on-court interview. “Also for the [past] 10, 15 years, he’s been an inspiration to watch on TV the way he fights and always finds a way to never give up.”

“It’s been an unfortunate couple of years for him, but it’s great to see him back and I think he was playing at a high level today.”

San Diego wild card Murray thumped American Denis Kudla 6-3, 6-2 in the first round but the three-time major champion managed to win just 51 percent of his service points and lost serve five times.

READ | Andy Murray: If my ranking allows, I will strongly consider playing Laver Cup

Ruud lost his serve while serving for the match at 5-3 in the second set, but broke Murray again in the next game to prevail.

Picture: Casper Ruud – ATP Tour/Twitter